US2387501A - Hydrocarbon oil - Google Patents

Description

Patented Oct. 23, 1945 HYDROCARBON OIL Melvin A. Dietrich, Claymont, Del., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application April 4, 1944,

Serial No. 529,512

14 Claims.

This invention relates to hydrocarbon oils and (c1. est-47.5)

more particularly to hydrocarbon oil compositions having low pour points, high viscosity indexes and improved stability against breakdown underoxldizing conditions.

Hydrocarbon oils, derived from paraflin and mixed base crude oils, contain considerable amounts of parafl'in wax which causes the oil to become solid at low temperatures and, in the case of lubricating oils, prevents a quick and effective flow of the lubricant to moving parts. Such wax may be removed from the oil by cold settling or by dilution with low boiling naphtha followed by chilling and centrifuging or filtration. These processes are expensive and may, if complete removal of the wax is effected, result in lubricants with reduced viscosity indexes. In'the low viscosity mineral oils, such as those boiling above the kerosene range and which are used as fuels in compression-ignition engines, the presence of wax may result in congelation of the oil in storage tanks at low temperatures. Complete removel of thewax may result in a fuel with unsatisfactory combustion characteristics.

The change in the viscosity of oils, with variations in temperature, is well known. A high rate of change of viscosity with change in temperature is generally considered undesirable since, for

low viscosity for use at high temperatures and too high viscosity for use at low temperatures. In the case of fuel oils, too rapid change of viscosity with change in temperature may result in unsatisfactory carburetion and poor combustion of the fuel.

Hydrocarbon oils, on being subjected to the action of heat, air and metals, tend to oxidize and form insoluble products which deposit in oil lines, heat exchangers, crankcases, storage tank and the like. These deposits generally result in reduced flow of oil to the bearing surfaces and may shut off such flow altogether by clogging oil holes.

Many substances have been proposed for addition to hydrocarbon oils for the purpose of improving the properties of the oils in each of the above respects. Such substancesinclude polymerized olefines, condensation products of arcmatic hydrocarbons with chlorinated paraflln wax, mixed aryl alkyl ketones, and fatty acids and their salts and esters. These various substances have been found to act withvarying degrees of efilciency in improving the properties of the oil with respect to one of the characteristics above discussed,but generally have no beneficial effect on other properties of the oil. This has generally made it necessary to add several different suba many lubricant uses, it results in an oil with too stances to an oil in order to obtain the desired effect on the different properties of the oil. This is objectionable and those skilled in the art have long searched for a single substance which will improve the pour point, the viscosity index and the stability of the oil against oxidative breakdown.

It is an object of the present invention to provide a material for addition to hydrocarbon oils to improve the various properties of the oil. A particular object of my invention is to provide hydrocarbon oils with reduced pour points and improved flow characteristics at low temperatures. Another particular object of my invention is to provide a hydrocarbon oil with a low rate of change of viscosity with change in temperature, that is, with a high viscosity index. A further particular object of the present invention is .to provide a hydrocarbon oil having a high resistance to oxidation and a reduced tendency to form insoluble products under oxidizing conditions. A still further object is to provide a hydrocarbon oil which is improved with respect to pour point, viscosity index and stability against oxidative breakdown.

The above and other objects may be accomplished in accordance with my invention which comprises incorporating in a hydrocarbon oil a small proportion of an oil-soluble polymeric N- aliphatic acrylamide having a molecular weight of at least 1000 in which the aliphatic group contains an open chain of at least 8 atoms of which not more than 2 are interrupting atoms of the group of oxygen and sulfur and the rest are carhon atoms. I have found that such polymeric acrylamides, when incorporated in a hydrocarbon oil, are very effective to reduce the pour point,

I increase the viscosity index and increase the stability of the oil against oxidative breakdown. Thus, by m invention, I am able to improve several properties of a hydrocarbon oil by the incorporation therein of a single substance.

The oil-soluble polymeric N-aliphatic acrylamides, which are to be employed in accordance with my invention, may be defined'as polymers whose monomeric unit is considered to be wherein each of R and R. represents a hydrogen atom or an aliphatic hydrocarbon group and R" is an acyclic aliphatic group containing a chain of at least 8 atoms, not more than 2 of which atoms are interrupting atoms of oxygen or sulfur and the rest of which atoms are carbon atoms. These compounds may be obtained by the reaction of the appropriate amine with an acrylic acid ester which may be monomeric or polymeric.

The acrylic acid esters, from which my compounds may be derived, may be represented by the formula wherein R represents a hydrogen atom or an aliphatic hydrocarbon group and R represents an esterifying organic group. Preferably, R will represent hydrogen or a short-chain alkyl group, such as methyl, ethyl and propyl. Also preferably, R' will be a short-chain alkyl group. Representative acrylic acid esters are the esters of acrylic acid, methacrylic acid, ethylacrylic acid and propylacrylic acid. v

The amines, which may be employed in the preparation of the amides, which are to be employed in accordance with my invention, may be represented by the formula wherein R represent hydrogen or an aliphatic hydrocarbon group and R" represents an aliphatic group which contains an open chain of at least 8 atoms, not more than 2 of such atoms being interrupting oxygen or sulfur atoms and the rest of such atoms being carbon atoms. The aliphatic chain, represented by R, may be a straight chain or a branch chain and may be saturated or unsaturated. Generally, it will be preferred that R" be a hydrocarbon group, that is, one which consists of carbon and hydrogen. However, the chain represented by R" may be substituted by other elements or groups, such as halogens, nitro and divalent sulfur-containing and oxygen-containing groups, particularly in the form of ether or thioether linkages. Representative of such substituents are chlorine, fluorine, nitro, ethoxy, isobutyloxy, benzylthio, benzyl,

cyclohexyl, naphthyl and naphthylthio. Prefer-v ably, the amines will be primary amines, that is, those in which R. represents hydrogen. Primary amines, derived from vegetable, animal or fish oils or by the oxidation and amination of paraffin or other petroleum fractions, may be used. Amines, derived from hydrogenated coconut oil alcohols and naphthenyl amines, are especially useful. By the term alkyl group, as employed herein, I mean a saturated aliphatic hydrocarbon group.

The polymeric N-aliphatic acrylamides, employed in accordance with my invention, may be prepared by the polymerization of monomeric acrylamides or by heating polymeric acrylic esters with the appropriate amine until substitution has taken place. Generally, more effective products are obtained by reacting the amine with the polymeric acrylic esters. The reactants will be mixed and heated together at temperatures sufliciently high to decompose the ester and drive off the esterifying alcohol. The temperature employed will be determined by the ease of the reaction and by the boiling point and mixtures of amines may be employed in the reaction.

The polymeric amides will vary from gummy materials, which can be pulled into threads and filaments, to soft rubbery materials and materials which resemble a soft tough glass at ordinary temperatures. They will have molecular weights which may vary from 1000 to as high as 50,000. Preferably, I employ polymers having a molecular weight of from about 5000 to about 25,000.

By a hydrocarbon oil, I mean one which has a viscosity of at least 35 seconds Saybolt at F., and intend to include therein oils in the fuel oil range, including Diesel fuels and furnace oils, as well as the higher viscosity. oils, employed as lubricating oils and greases. The oils may be solvent extracted oils or conventionally refined oils, obtained from various base crude oils. They may be specially compounded oils, such as those containing lard oil, 'fish oil, castor oil or the like. When the oils are fuel oils, designed for use in high speed Diesel engines, they may contain ignition primers, such as ethyl nitrate. The polymeric materials may be added to refined-oils or may be added to the oils during any suitable stage in therefining process. The use of the polymeric amides of my invention in fuel oils is of considerable importance since it permits the manufacture and use of fuel oils of higher paraflin content and improved ignition qualities.

The quantity of polymer to be added to the oil will vary within wide limits and will depend on the effect it is desired to produce. Thus, if pour point depressant action alone is desired, as little as 0.01% may suffioe with the preferred range lying between 0.02% and about 1.0%. If improvement of viscosity index is the main consideration a larger amount of polymer will normally be required, the preferred quantity ranging from about 1.0% to about 5.0%. In fuel oils, preferred ranges of concentration lie between about 0.01% and about 5.0%. The products may be used in conjunction with other additives such as organic phosphates or phosphites, for example, tricresyl phosphate or tributyl phosphite; metal soaps or additives, for

example, copper naphthenate, tin oleate, chro-.

mium oleate, or copper derivatives of terpene mercaptans; sulfur-containing stabilizers, such as sulfurized sperm oil, S-alkylated Z-mercaptothiazolines, and dialkylthiuram disulfides.

The products may be used in mineral oils for the preparation of greases. In this case, higher concentrations, than those mentioned heretofore, may be needed. Thus, concentration ranges of about 5.0% to about 50.0% may be needed to produce greases of satisfactory consistency. In the preparation of greases, the polymers may be used in conjunction with metal soaps such as sodium, calcium, lithium, aluminum, and barium naphthenates or stearates.

The polymeric amides of my invention may be employed in refining oils in conjunction with solvent dewaxing processes whereby a more efficient separation of wax occurs and a product of very low pour point is obtained. In the dewaxing of paraflin base oils, the distillate is mixed with a solvent naphtha, the mixture is chilled to about --20 F. and then filtered or centrifuged to remove the precipitated wax. This wax contains considerable amounts of absorbed oil which requires removal to obtain a high melting and commercially useful paraflln. The

aseaeoi addition of the polymeric amides oi my inven tion to the solvent naphtha-oil mixture, prior to chilling; produces a wax which contains lesser amounts of absorbed oil than it would otherwise contain. This results in high yields of the dewaxed oils as well as a better wax. At the same time, the dewaxed oil thus obtained has its properties improved by the presence oi the polymeric amide which is carried through the process with the oil.

In order to more clearly illustrate my inven tion, the preferred modes of carrying the same into effect and the advantageous results to be obtained thereby, the following examples are given in which the amounts are by weight, except where otherwise specifically indicated.

' Example 1 were noted:

Origi- Oil 2 na] oil polymer Seybolt Universal viscosity at 100 F .seconds-. Saybolt Universal viscosity at 210 F. ...do Viscosity index The viscosity index noted above was calculated by the method of Dean and Davis described in Chem. and Met. Eng. 36, 618 (1929). This index serves as a measure of the flatness oi the viscosity-temperature curve. With increasing values of the index, viscosity-temperature curves become flatter.

Example II Ten parts of methyl methacrylate polymer and 2''! parts or octadecylamine were mixed and heated to 250 C. for one hour. The reaction mass was dissolved in benzene, filtered, and evaporated in vacuo. The residue was a gummy gray material which could be pulled into threads and filaments and which weighed 33 Parts. It contained 37.4% nitrogen. The eflect or this material on pour point is shown as follows:

Pour point of BAE 30 paraiiin base Percent by weight of polymer in oil A 2% solution in the paraffin base distillate given in Example. I raised the viscosity index from 92 to 115. The characteristics or the treated oil were: viscosity at 100 .F., 359 seconds; at 210 F., 59.1 seconds.

Example 111 A second batch of product, prepared as described in Example H, was dissolved in a solventreflned Mid-Continent BAE 30 oil to form a 0.5%

solution by weight. This 011 was then tested for This mate- 3 stability against formation of deposits by the method described in U. S. 2,236,168. The results obtained are as follows:

Deposit, mg/30 cc. oil

Untreated oil 232 Treated il 1633 Reduction in deposit .'-per cent 30 Example ill Twenty parts of polymeric methyl methacrylate and 53 parts of oleylamine were mixed and heated for 2 hours at 250 C. with stirring. The mass was cooled, dissolved in benzene, filtered, and

evaporated in vacuo. Seventy parts of a soft rub bery polymer were obtained. A 2% solution or this product in an SAE 30 paramn base oil. yielded the following viscosity data:

The stability of the product under service conditions was demonstrated by means of an engine test, using a 0.33% oil solution of the product, prepared as in Example 11 from octadecylamine and methyl methacrylate polymer. The oil had an initial pour point, prior to treatment with the polymer, of 25 F. After treatment to'form a temperature of 250. F. and a jacket temperature of 160 F. At the end of this period the pour 40 point of the oil was -5 F., substantially the same as the pour point at the start of the test.

, It will be understood that the preceding examples are given for illustrative purposes only and that various modifications and variations .may be made therein without departing from the spirit or scope or my invention, my invention not being limited to the specific embodiments disclosed, except as indicated in the following claims. For example, in addition to the substances employed in the examples, the following polymeric amides come within the scope of this invention:

m an N-methyi-N-octadecylpolymethacryiamide N-propyl-N-octadecenylpolymethacrylamide N-2ethylhexylpolyethylacrylamide N-octadecyl polyethylacrylamide N-octadecenyl polyethylacrylamide N-2-ethylhexylpolyacrylamide N-octadecylpolyacrylamide N-hexadecylpolyacrylamide N-ethyl-N-octadecyi polyacrylamide N-hexyi-N (w-carboxy) undecyl polymethacry amide N-(b-dodecylthio) ethyl polymethacrylam'ide N-(b-octylthio) ethyl polyacrylamide N-(b-decyloxy) ethyl polyethylacrylamide N-(b-amylthio) ethyl polymethacrylamide N-(b-isoamyloxy) ethyl polypropyiacrylamide It will be apparent from all of the above that, by my invention, I have provided hydrocarbon oils which have been improved in a number of their properties and which have many uses, such as in the lubrication of internal combustion engines, for bearings subjected to high speeds and pressures, for the lubrication of gears of the hypoid, spiral and bevel types, for railroad rolling stock, for marine engines and for protective coatings on metallic surfaces subject to corrosion.

I claim:

1. A hydrocarbon oil having incorporated therein a small proportion, at least 0.01%, of an oil-soluble polymeric N-aliphatic acrylamide having a molecular weight of at least 1000 in which the aliphatic group contains an open chain of at least 8 atoms of which not more than 2 are interrupting atoms of the class consisting of oxygen and sulfur and the rest are carbon atoms.

2. A hydrocarbon oil having. incorporated therein a small proportion, at least 0.01% of an oil-soluble polymeric N-aliphatic acrylamide having a molecular weight of at least 1000 in which the aliphatic group contains an open chain of at least 8 carbon atoms.

. 3. Ahydrocarbon oil having incorporated therein a small proportion, at least 0.01%, of an oilsoluble polymeric N -aliphatic acrylamide having a molecular weight of at least 1000 in which the aliphatic group is an open chain hydrocarbon group containing at least 8 carbon atoms in the chain.

4. A hydrocarbon oil having incorporated therein a small proportion, at least 0.01%, of an oilsoluble polymeric N-alkyl acrylamide having a molecular weight of at least 1000 in which the alkyl group contains an open chain of at least 8 carbon atoms.

5. A hydrocarbon oil having incorporated therein a small proportion, at least 0.01%, of an oilsoluble polymeric N-octadecyl acrylamide having a molecular weight of at least 1000.

6. A hydrocarbon oil having incorporated therein a small proportion, at least 0.01%, of an oilsoluble polymeric N-octadecyl methacrylamide having a molecular weight of at least 1000.

7 A hydrocarbon oil having incorporated therein a small proportion, at least 0.01%, of an oilsoluble polymeric N-aliphatic acrylamide having a molecular weight of at least 1000 which is the reaction product of a polymeric acrylic acid ester and an aliphatic amine containing an open chain of at least 8 atoms of which not more than 2 are interrupting atoms of the class consisting of oxygen and sulfur and the rest are carbon atoms.

8. A hydrocarbon oil having incorporated therein a small proportion, at least 0.01 of an oilsoluble polymeric N-aliphatic acrylamide having a molecular weight of at least 1000 which is the reaction product of a polymeric acrylic acid ester and an aliphatic amine which, except for theamino N atom, consists of carbon and hydrogen and contains an open chain of at least 8 carbon atoms. 1

9. A hydrocarbon oil having incorporated therein a small proportion, at least 0.01%, of an oilsoluble polymeric N-alkyl acrylamide having a molecular weight of at least 1000 which is the reaction product of a polymeric acrylic acid ester and an alkyl amine containing an open chain of at least 8 carbon atoms.

10. A hydrocarbon oil having incorporated therein a small proportion, at least 0.01%, of an oil-soluble polymeric N-octadecyl acrylamide having a molecular weight of at least 1000 which is the reaction product of a polymeric acrylic acid ester and octadecylamine.

- oil-soluble polymeric N-aliphatic acrylamide having a molecular weight of at least 1000 which is the reaction product of a polymeric methacrylic acid ester and an aliphatic amine containing an open chain of at least 8 atoms of which not more than 2 are interrupting atoms of the class consisting of oxygen and sulfur and the rest are carbon atoms.

12. A hydrocarbon oil having incorporated therein a small proportion, at least 0.01 of an oil-soluble polymeric N-aliphatic acrylamide having a molecular weight of at least 1000 which is the reaction product of a polymeric methacrylic acid ester and an aliphatic amine which, except for the amino N atom, consists of carbon and hydrogen and contains an open chain of at least 8 carbon atoms.

13. A hydrocarbon oil having incorporated therein a small proportion, at least 0.01%, of an oil-soluble polymeric N-ali-phatic acrylamide having a molecular weight of at least 1000 which is the reaction product of a polymeric methacrylic acid ester and a primary aliphatic amine which, except for the amino N atom, consists of carbon and hydrogen and contains an open chain of at least 8 carbon atoms.

14. A hydrocarbon oil having incorporated therein a small proportion, at least 0.01%, of an oil-soluble polymeric N-octadecyl acrylamide having a molecular weight of at least 1000 which is the reaction product of a polymeric methacrylic acid ester and octadecylamine.

MELVIN A. DIETRICH.